Disinfection of water is required to insure the destruction of pathogenic organisms. Maintenance of a halogen residual in the water is the usual method of guarding against sanitary defects or accidents that may occur during the production, handling, storage and distribution of water. The absence of a free available chlorine (FAC) or total bromine residual (TBR) in a water system may indicate contamination. The presence of a halogen residual provides an indication that the water is free of pathogenic organisms. A generally accepted rule is an FAC or TBR of 0.2 parts per million (ppm) after 30 minutes contact time. It is also generally accepted that free halogen residual concentrations as high as 2.0 ppm do not cause objectionable tastes and odors. These values of FAC and TBR, 0.2 ppm and 2.0 ppm, thus represent typically encountered halogen application levels, although special circumstances can demand higher levels.
One of the methods by which bromine is introduced into a water system is via a cartridge containing a polybromide impregnated resin. The water being treated is allowed to flow through the cartridge. Ionic action between the water and the resin allows bromine to elute off the resin and enter the water. The rate at which the bromine elutes into the water is a function of the water temperature, water flow rate through the cartridge and the cartridge life cycle age. Consequently, the effective life cycle of a cartridge is also a function of the same variables. Currently, bromination systems do not accurately determine when the end of the effective life of a cartridge is reached. Estimates based on water volume and temperature are used to determine if a cartridge is at the end of its life cycle. In most cases, these estimates are inaccurate and many cartridges are discarded when they are only 50-75% into their life cycle. Also, with current systems, the cartridge cannot be viewed to see how far down on the cartridge the interface between bromine rich resin (reddish color) and bromine depleted resin (grayish color) is located without shutting the system down and disassembling the cartridge housing.
The invention broadly embodies a system and method for accurately determining when the life cycle of a bromine cartridge is completed.
In a preferred embodiment, the bromine content of the supply water is measured. When the bromine content remains below a predetermined level over a pre-determined period of time, a signal is output from the sensoring device indicating that a new cartridge should be placed on line.
In a preferred embodiment of the invention, a two pole halogen, e.g. bromine, sensor is placed into a water stream to sense the presence or absence of a designated quantity of bromine in the stream. A voltage potential between the two poles of the sensor is a function of the bromine level in the water stream. The absence of the designated bromine level in the water will cause the potential between the poles of the sensor to change causing the circuitry in a controller to energize a pre-set timer and actuate a valve. The actuated valve will open and allow water to flow through a cartridge containing polybromide impregnated resin. Ionic action between the water and the resin will allow bromine to elute off the resin and enter the water stream. A pump continually circulates the water through the system and over the sensor. If the level of bromine is not increased to the designated level within the pre-set time of the energized timer, then the effective bromine contained in the cartridge is depleted. When these two conditions are met (timing out of the timer and deficient bromine level), circuitry in the controller will energize an indicating device or devices.
In the case where multiple polybromide impregnated resin cartridges are used in the system, they are housed in clear vessels. These clear vessels will allow an operator to observe visually the polybromide impregnated resin cartridge without shutting the system down. By observing how far down on the cartridge the interface between bromine rich resin (reddish color) and bromine depleted resin (grayish color) is located on each cartridge, the operator can choose to replace the most depleted cartridge.